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package org.zwobble.couscous.tests.interpreter;
import org.junit.Test;
import org.zwobble.couscous.MapBackedProject;
import org.zwobble.couscous.ast.Assignment;
import org.zwobble.couscous.ast.ClassNode;
import org.zwobble.couscous.ast.ExpressionStatementNode;
import org.zwobble.couscous.ast.FormalArgumentNode;
import org.zwobble.couscous.ast.LiteralNode;
import org.zwobble.couscous.ast.MethodNode;
import org.zwobble.couscous.ast.ReturnNode;
import org.zwobble.couscous.interpreter.Interpreter;
import org.zwobble.couscous.interpreter.VariableNotInScope;
import org.zwobble.couscous.interpreter.WrongNumberOfArguments;
import org.zwobble.couscous.values.ConcreteType;
import org.zwobble.couscous.values.InterpreterValue;
import org.zwobble.couscous.values.StringValue;
import com.google.common.collect.ImmutableMap;
import static java.util.Arrays.asList;
import static org.junit.Assert.assertEquals;
import static org.zwobble.couscous.ast.LiteralNode.literal;
import static org.zwobble.couscous.ast.LocalVariableDeclarationNode.localVariableDeclaration;
import static org.zwobble.couscous.ast.MethodNode.staticMethod;
import static org.zwobble.couscous.ast.VariableReferenceNode.reference;
import static org.zwobble.couscous.tests.util.ExtraAsserts.assertThrows;
import static org.zwobble.couscous.values.UnitValue.UNIT;
import lombok.val;
public class InterpreterTests {
@Test
public void methodWithNoStatementsReturnsUnit() {
val method = staticMethod("hello");
val result = runMethod(method);
assertEquals(UNIT, result);
}
@Test
public void canReturnLiteralValue() {
val method = staticMethod("hello")
.statement(new ReturnNode(LiteralNode.literal("hello, world!")));
val result = runMethod(method);
assertEquals(new StringValue("hello, world!"), result);
}
@Test
public void canPassValueToMethod() {
val arg = new FormalArgumentNode(42, StringValue.REF, "x");
val method = staticMethod("hello")
.argument(arg)
.statement(new ReturnNode(reference(arg)));
val result = runMethod(method, new StringValue("hello, world!"));
assertEquals(new StringValue("hello, world!"), result);
}
@Test
public void errorIfWrongNumberOfArgumentsArePassed() {
val method = staticMethod("hello");
val exception = assertThrows(WrongNumberOfArguments.class,
() -> runMethod(method, new StringValue("hello, world!")));
assertEquals(new WrongNumberOfArguments(0, 1), exception);
}
@Test
public void canReassignValueToArgument() {
val arg = new FormalArgumentNode(42, StringValue.REF, "x");
val method = staticMethod("hello")
.argument(arg)
.statement(new ExpressionStatementNode(new Assignment(reference(arg), LiteralNode.literal("[updated value]"))))
.statement(new ReturnNode(reference(arg)));
val result = runMethod(method, new StringValue("[initial value]"));
assertEquals(new StringValue("[updated value]"), result);
}
@Test
public void canDeclareVariable() {
val localVariableDeclaration = localVariableDeclaration(
42, StringValue.REF, "x", LiteralNode.literal("[initial value]"));
val method = staticMethod("hello")
.statement(localVariableDeclaration)
.statement(new ReturnNode(reference(localVariableDeclaration)));
val result = runMethod(method);
assertEquals(new StringValue("[initial value]"), result);
}
@Test
public void canDeclareVariableAndThenAssignValues() {
val localVariableDeclaration = localVariableDeclaration(
42, StringValue.REF, "x", LiteralNode.literal("[initial value]"));
val method = staticMethod("hello")
.statement(localVariableDeclaration)
.statement(new ExpressionStatementNode(new Assignment(reference(localVariableDeclaration), LiteralNode.literal("[updated value]"))))
.statement(new ReturnNode(reference(localVariableDeclaration)));
val result = runMethod(method);
assertEquals(new StringValue("[updated value]"), result);
}
@Test
public void errorIfTryingToAssignToVariableNotInScope() {
val localVariableDeclaration = localVariableDeclaration(
42, StringValue.REF, "x", literal(""));
val method = staticMethod("hello")
.statement(new ExpressionStatementNode(new Assignment(reference(localVariableDeclaration), LiteralNode.literal("[updated value]"))));
val exception = assertThrows(VariableNotInScope.class,
() -> runMethod(method));
assertEquals(new VariableNotInScope(42), exception);
}
private InterpreterValue runMethod(MethodNode.MethodNodeBuilder methodBuilder, InterpreterValue... arguments) {
val method = methodBuilder.build();
val className = "com.example.Program";
val classNode = ClassNode.builder(className)
.method(method)
.build();
val interpreter = new Interpreter(new MapBackedProject(ImmutableMap.of(
className, ConcreteType.fromNode(classNode))));
return interpreter.run(className, method.getName(), asList(arguments));
}
}
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